Devices for selectively directing inflation devices

ABSTRACT

Devices have been made which are balloon catheters, preferably PTCA devices, and which are capable of selectively directing inflation forces against the thicker part of an eccentric arterial obstruction or an off-center plaque deposit. In a first embodiment, a balloon catheter is formed from at least two balloons positioned side-by-side to each other. One balloon is larger in diameter than the other balloon(s). The larger diameter balloon acts as a cushion to the thinner part of a lesion. The small balloon(s) focuses greater inflation force against the thicker part of the lesion. In a second embodiment, a unitary balloon catheter has a plurality of independently inflatable lobes. Inflation forces may be selectively directed depending on which lumen of the balloon catheter is pressurized. Additionally, different lumens can be used for other purposes including an auto-perfusion catheter and monorail applications. The new devices provide a method of opening a constricted region in the cardiovascular system of a patient.

This is a continuation of application Ser. No. 08/029,447, filed on Mar.11, 1993, now abandoned.

FIELD OF THE INVENTION

This invention relates to balloon catheters which are especially usefulfor opening a constricted region in the cardiovascular system of apatient in which the constricted region is non-concentric or eccentricrelative to the diameter of the cardiovascular vessel.

BACKGROUND OF THE INVENTION

Coronary angioplasty has emerged as a viable present alternative tobypass surgery for revascularization of stenotic and occluded coronaryarteries. Percutaneous coronary angioplasty is less invasive and lesstraumatic to the patient and is less expensive since the angioplastypatient will have a shorter hospital stay and a shorter post-procedurerecovery time.

Percutaneous transluminal angioplasty is performed by use of a catheterwhich has a built-in inflatable and deflatable balloon. The ballooncatheter can be passed through a guiding catheter and advanced inside atarget artery toward the point of obstruction that needs to be dilated.When the balloon portion of the catheter is properly positioned insidethe arterial obstruction, the balloon is inflated to a pressuresufficient to overcome the resistance of the arteriosclerotic plaque ofthe obstructed site. By inflating the balloon in the stenosis multipletimes over a period of time, the desired dilation of the obstructedsegment of the artery can be achieved.

The distribution of atherosclerotic plaque in coronary arteries can havetwo major types of cross-sectional luminal shapes, concentric andeccentric. If the plaque is distributed evenly along the entirecircumference of the arterial internal elastic membrane, the coronarylumen is located centrally and is called a concentric type lesion. Ifthe plaque does not involve the entire arterial circumference leaving avariable arc of disease-free wall (normal wall), the residualcross-sectional lumen is called eccentric. More often than not, thelumen through a stenosis is off center and rarely round. Recent studieshave found that a high percentage of arterial lesions are eccentric.

Ischemic complications of percutaneous translumina coronary angioplasty(PTCA) occur in a significant number of patients and constitute a majorcause of morbidity and mortality associated with PTCA. Variable degreesof intimal and media and plaque disruption occur during all PTCAprocedures and may vary from mild superficial splitting to grossfissuring through the entire medial and plaque mass.

As noted above, coronary occlusions are not always concentric relativeto the diameter of the artery and, in fact, most such lesions have beenfound to be eccentric. The use of PTCA in a patient with an eccentricstenosis does not necessarily move the bulk of the stenotic material outof the arterial lumen. Very often, the thinner side of the lesion givesway and the artery wall gives way with it. Media layer tear ordissection is common. Although lumenal space is increased therebyincreasing blood flow by the lesion, extensive damage may be done to thearterial wall. This damage is well documented in the followingreferences:

"The Eccentric Coronary Atherosclerotic Plaque: Morphologic Observationsand Clinical Relevance". B. F. Waller, M.D. Clinical Cardiology 12,14-20 (1989)

"Morphologic Correlate of Coronary Angiographics Patterns at the Site ofPTCA". B. F. Waller, M.C. Clinical Cardiology 11,817-822 (1988)

"Morphology of Coronary Lesions in the Prediction of Early PTCAOutcome". Haft et al, Catherization and Cardiovascular Diagnosis 17:69-74 (1989)

"Tear or Dissection After Coronary Angioplasty". King et al,Circulation--Volume 79, May 1989 pp. 1035-1041

"Vessel Plaque and Lumen Morphology After Transluminal BalloonAngioplasty". Lyon et at, Arteriosclerosis, Vol. 7, No. 3, May/June 1987

"Stress Analysis of the Diseased Arterial Cross Section". Vito, Whang,Giddens, Zadns, Glagov 1990. Advances in Bioengineering ASME, BED--Vol.17

Very often balloon dilatation results in a situation where media andintima split along with the thin section of the stenosis. Because ofmaterial property (mechanical) differences within the stenotic material(it is not homogenous) and between the artery walls and the stenosis,delamination of the stenosis can also occur.

Detection of non-concentric lesions is easily done by using orthogonalviews of the same anatomical area. Some lesions may look very minor inone view, but, when the same lesion is viewed at a fight angle to thefirst view, it may then seem extremely restrictive. Orthogonal viewingof the coronary arteries is very common and a long standing practice.

The consequence to lesion dissection is flow disruption which may leadto thrombus formation and early re-occlusion. It was hoped that the LABA[Laser Assisted Balloon Angioplasty] device would mitigate this problem.However, restenosis rates were not improved by this device.

The prior art includes patents disclosing a plurality of balloonspositioned on the distal end of a dilation catheter as well as patentsdisclosing a plurality of lumens (luminae) having an inflatable lobe incommunication with a respective tureen.

U.S. Pat. No. 4,787,388 to Hofmann discloses a multi-lobed ballooncatheter having three lobes (balloons) that are independently andselectively inflatable by air passing through respective lumenscommunicating with the lobes. The Hofmann patent specifically teaches,however, that it is preferable for the balloons to be inflated together,such as from a common source (Col. 2, lines 46-54). The three balloonsof the Hofmann catheter are formed independent from each other and forma triangular configuration (FIG. 3B). Because the balloons are separatefrom each other, the area between the balloons form passages which allowfluid flow between the balloons, thus forming a perfusion catheter. Theballoons are substantially equal in size and preferably inflatedtogether.

U.S. Pat. No. 5,071,406 to Jang discloses a balloon dilatation catheterhaving two or more independently inflatable balloons (FIG. 7) positionedon opposite sides of a catheter shaft. The first balloon has a longerlength than the second balloon. The balloons share some common walls,and form a catheter construction having three effective diameters.

The catheter in Jang is constructed so that multiple balloons are formedfrom a single, monolithic piece of polymer material. This constructionprovides a smooth transition from balloon to balloon on the outside ofthe catheter. The balloons are formed so that one balloon may be longerand larger than the other balloon. One balloon is inflated while theother is deflated and, later, the inflated balloon is deflated and thedeflated balloon inflated. The respective size of the inflated balloonsthus varies for use in several stenoses or multi vessels.

U.S. Pat. No. 4,083,369 to Sinnreich discloses a surgical device used ingynecology. The device includes an inflatable balloon element formed ofa relatively thicker wall area and an opposing thinner wall area. Whenthe device is inserted within a body cavity, such as a uterus, thethinner wall area is adapted for contacting the raw tissues within abody cavity while the thicker wall section faces toward the lesssensitive tissues, such as the forward abdominal wall.

U.S. Pat. No. 5,102,416 to Rock discloses a catheter having threeexpandable chambers that are selectively pressurized to cause thechambers to distend asymmetrically about the catheter's axis so that thecatheter can be easily directed within a patient's venal system. Later,the chambers are equally inflated to provide a balloon which issymmetrical for use during an angioplasty procedure.

Other patents to Jang besides the '406 patent mentioned above includeU.S. Pat. Nos. 4,744,366; 4,763,654; 4,958,634; and 4,990,139. Thesepatents disclose concentrically arranged balloons, and balloons that arepositioned proximal and distal to each other.

U.S. Pat. No. 5,108,370 to Walinsky discloses a perfusion ballooncatheter in which the outer membrane forming the balloon is selectivelyconnected to the inner tube of the catheter forming a perfusion tureenbetween a vascular wall and the outer membrane.

U.S. Pat. No. 5,000,734 to Boussignac et al discloses a probe having abag element (balloon) with at least one perfusion conduit formed in thebag.

Other patents disclose multiple balloons, either positioned tandem toeach other, or concentric to each other. Examples include U.S. Pat. Nos.4,445,892; 4,778777; 4,748,981; 4,986,830; 4,994,033; 5,002,532; and5,049,132.

Other patents disclose multiple lumen catheters such as U.S. Pat. Nos.4,584,998 and 4,846,791.

There is a continuing need to provide safer and more efficient PCTAdevices which can be used to help all patients including those havingeccentric coronary occlusions.

It is an object of the present invention to provide unique PCTA deviceswhich can focus the inflation energy of the balloon portion to aspecific point on an arterial lesion.

It is further object of the present invention to provide the ability ina PCTA procedure to direct the dilating force(s) in desireddirection(s).

It is a still further object of the present invention to provide a PCTAdevice which eliminates or minimizes the possible occurrence of arterialwall damage.

SUMMARY OF THE INVENTION

The present invention relates to devices which are balloon catheters,preferably PTCA devices, and which are capable of selectively directinginflation forces against the thicker part of an eccentric arterialobstruction or an off-center plaque deposit.

In a first embodiment of the present invention, a balloon catheter isformed from at least two balloons positioned side-by-side to each other.One balloon is larger in diameter than the other balloon(s). The largerdiameter balloon acts as a cushion to the thinner part of a lesion. Thesmaller balloon(s) focuses greater inflation force against the thickerpart of the lesion.

In a second embodiment of the present invention, a unitary ballooncatheter has a plurality of independently inflatable lobes. Inflationforces may be selectively directed depending on which lumen of theballoon catheter is pressurized. Additionally, different lumens can beused for other purposes including an auto-perfusion catheter andmonorail applications.

By using the devices of the present invention, inflation pressure from aballoon is focused on the "thick" part of the lesion and not on the"thin" part. Hence, the vessel wall adjacent to the thin section may notbe as affected. This is done, for example, by using two balloons side byside in the lesion with differing diameters. If the larger diameterballoon is inflated at a low pressure adjacent to the thin part of thelesion cross section and a small diameter balloon is inflated to ahigher pressure adjacent to the thicker part, the larger diameterballoon acts as a cushion against the thin part. The force of the largerballoon is spread over a larger area while the smaller balloon inflationforce is focused on the fat part of the lesion. This results in afracture through the thicker portion of the lesion.

In the first embodiment of the present invention, the device has atleast three lumens. At least two of the lumens independently inflate theballoons and one can carry a guide wire. The shaft is made of amulti-lumen extrusion or of a variation of coaxial arranged tubes. Threesmaller tubes are placed in a larger tube to contain them as one shaft.There may be advantages to free floating tubes within a larger tube inflexing around bends. A multi-lumen tube might not be as flexiblebecause of its integral structure.

One of each of the inflation tubes terminates inside each balloon whilethe lumen for the guide wire passes between the balloons and ends distalto the distal extremity of the balloons. The distal portions of theballoons are bonded to the distal end of the guide wire lumen. In amulti-lumen design, the shaft ends at the proximal segment of theballoons and the lumens are separated to connect to each balloon. A tipsection can also be added to extend past the balloons for the guidewire.

The second embodiment of the present invention comprises a unitarymulti-lumen (multi-lobe) dilation balloon in which the lumens (lobes)can be inflated independently or simultaneously of each other. Thisdilation balloon inflates to a non-round configuration. Each of themultiple lumens will naturally inflate round while the combination ofall the lumens will inflate to a non-round geometry or configuration asa function of the number of lumens (lobes). This design allows the useof high pressure as a result of small lumens and provides advantageousfolding properties. Because of the ability to independently inflate thelumens (lobes), there is a consequent ability to direct the dilationforces in desired directions. The resultant non-round balloon of thepresent invention applies greater forces in a desired direction.

The present invention also comprises a novel method of opening aconstricted region in the cardiovascular system of a patient comprisesthe use of the novel PTCA devices of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a cross-section of a concentric stenosis and concentricstretching

FIG. 2 shows a cross-section of eccentric stenosis and dilation ofdisease free wall

FIG. 3 shows a cross-section of typical non-concentric (eccentric)stenosis

FIG. 4 shows a cross-section of a vessel after balloon dilation of aneccentric stenosis

FIG. 5 is a side elevation of the present asymmetric balloon dilationcatheter

FIG. 6a, are cross-sectional views of embodiments of the presentmulti-lumen 6b, 6c (lobe) dilation balloon and 6d

FIG. 7 is a side elevation showing an example of the present multi-lumen(lobe) balloon

DETAILED DESCRIPTION OF THE FIGURES

FIG. 1 shows a cross-sectional view of an obstructed artery 1. Thearterial wall 10 encompasses a concentric stenosis of obstruction 11within the arterial lumen 13. The figure shows a balloon 12 within thearterial lumen 13 which when inflated in the directions shown by thearrows compresses the stenosis or obstruction 11 as well as stretchesthe arterial wall 10. Because the stenosis or obstruction 11 isconcentric with the arterial lumen 13, the inflated balloon is able tocompress the stenosis or obstruction 11 in an even manner.

FIG. 2 shows a cross-sectional view of an obstructed artery 2 whereinthe artery contains an eccentric (non-concentric) stenosis orobstruction 21. The normal arterial lumen as shown by the dotted lines23 is partially blocked and the real arterial lumen actually present isshown at 22. The arterial wall at 24 is unobstructed. Because of theeccentric nature of the stenosis or obstruction, the arterial wall at 25causes the stenosis or obstruction at 21.

FIG. 3 shows a cross-section of another possible type of eccentric ornon-concentric stenosis or obstruction. In the figure, the obstructedartery 3 has an arterial wall 30 and lumina opening 33 is arc shapedbecause of the non-symmetric nature of stenosis or obstruction 34.Hence, if dilation is undertaken in such an obstruction with a prior artballoon catheter, intima 31 and media 32 will be subjected to unevenforces at one side of the artery as opposed to the side of the arteryhaving the "fat" portion 35 of the stenosis or obstruction 34.

FIG. 4 shows a cross-section of an eccentric or non-concentric arterysuch as shown in FIG. 3 after balloon dilation with a prior art ballooncatheter. The artery 4 of FIG. 4 has an arterial wall 40 with intima 41and luminal opening after dilation 43. Because of the uneven forceapplied to the fat end 45 of stenosis or obstruction 42 during dilation,a site of dissection 44 has occurred.

FIG. 5 shows a catheter 5 according to the present invention whichincludes two dilatation balloons 51, 52 that are located side-by-side onthe distal end of the catheter. One balloon 51 has a larger diameterthan the other balloon 52. In accordance with the invention, duringangioplasty, the smaller diameter balloon 52 is inflated to a higherpressure adjacent the thicker i.e., larger part of a lesion. The largerdiameter balloon, which is inflated at a lower pressure than the smallerballoon, "cushions" the thinner i.e., smaller portion of the lesion andspreads the inflation force over a larger area while the inflation forceof the smaller diameter balloon is focused against the thicker part ofthe lesion.

The catheter shaft 53 has three single lumens 54, 55, 56. Lumens 54, 55inflate the balloons 51, 52 independently, and the third carries aguidewire. Preferably, the shaft comprises coaxially arranged,free-floating tubes to provide maximum flexibility. It is alsopreferable that the catheter outer jacket, which contains the threesingle lumen tubes, be made torqueable with the addition of a wirebraid. This outer jacket may be constructed on a very thin wire in theorder of 0.001 to 0.002 inches and embedded and encapsulated by apolymeric material such as polyamide, polyethlene terephthalate (PET),polyethylene and similar such polymeric materials. Preferably the braidwire is made of a high tensile material such as stainless steel. Thebraid may also be formed from a Kevlar thread.

Preferably the catheter shaft diameter is less than or equal to about3.5 French (0.45") with a working length of about 135 cm. It is alsopreferable that the balloons are formed from a very strong material suchas PET with a wall thickness of about 0.00025 inches to reduce thecollapsible balloon in profile. The balloon diameters may range fromabout 1 mm to about 3 min.

FIGS. 6a, 6b, 6c, 6d and 7 show views of a multilobed balloon catheterin accordance with the present invention. The multilobed balloons ofFIGS. 6a, 6b, 6c, 6d and 7 have any number of lumens 61 which can beinflated independently of each other or simultaneously and also has ashaft opening 63. The number of lumens inflated at one time is optionaldepending on the desired application. The overall shape of the balloon6a, 6b, 6c, 6d or 7 is a function of the number of lumens (Lobes) or thenumber of inflated lumens (lobes) at any one time. Because of itsconfiguration, this balloon catheter can focus the dilatation forces indesired directions as opposed to round balloons which apply forcesequally in all directions. Also because of the small size of the lumensand corresponding smaller contact area of each lobe as compared with thelarger contact area of a single large uniform round balloon the ballooncatheter of the invention presents higher dilatation forces at each lobethan the single large balloon of the prior art.

In the PTCA device of the first embodiment of the invention, theballoons are not the same size, and are independently inflatable atdifferent pressures, the smaller balloon being inflated at a higherpressure than the larger balloon. The present asymmetric ballooncatheter also includes an outer jacket to hold the independent balloons(tubes) together.

It should be understood that while this first embodiment of theinvention includes one large balloon and a smaller balloon those skilledin the art would readily understand that embodiments including onelarger balloon and several smaller balloons are also encompassed withinthe scope of the present invention. It is clear that the larger balloonin any such embodiment functions as a cushion means to that portion ofthe diseased vessel which has a lesser degree or no degree of stenosisor obstruction.

In the other embodiment of the present invention, the multi-lumen,multi-lobed balloon catheter, has a plurality of independentlyinflatable lobes (balloons) forming different unique configurations,inflating to a non-round configuration. The overall balloon forms aunitary structure. Such balloons can be formed by using any knowntechnique including, for example, blow molding. This balloon catheterprovides effectively higher dilatation pressures at each lobe of higherpressure because of the smaller radius in each pressure component of theballoon, and also provides advantageous folding properties. Open tureenswhich are not being used to inflate lobes may be used to provide accessfor fluids or devices. For example, as shown in FIG. 7 some of thelumens 62 may be open from the proximal end of the balloon to the distalend thereof (not shown). These open lumens can be used to receive aguidewire which extends from the distal tip of the catheter, through theopen balloon lumen and proximally exterior to the catheter shaft to theproximal end of the catheter. As such the catheter can be operated in arapid exchange manner similar to that known in the art as discussed inU.S. Pat. No. B1 4,762,129 to Bonzel.

Alternatively, an open balloon lumen can be used to perfuse bloodthrough the balloon while the balloon is inflated to minimize traumathat would be otherwise caused by the balloon fully occluding the arterywhen the balloon is inflated. With the present multi-lumen (Lobe)balloon catheter comes the ability to direct dilating forces in desireddirections and without the need to position the balloon in order todirect the force. It is only required that the proper desired lumen(s)(Lobe(s)) be inflated. The present balloon allows the ability to have aballoon of a desired shape during dilation of a lesion and also allowsthe possibility of blood perfusion through the balloon. An additionaladvantage is the ability to pass a wire through the balloon for rapidexchange. It is believed that no other prior balloon can hold a shape atsuch high pressures as the present balloon nor does any prior balloonprovide open lumens through which fluids or devices can pass duringdilation of a lesion. The present balloon can be inflated into variousshapes depending upon the number of lobes which are present. Forexample, if there are three lobes and all are inflated, the shape wouldbe triangular. It is contemplated that the present balloon catheter canhave at least two lumen (lobes), preferably 2 to 10 lumens (lobes).Additionally, the cross-sections shape of the unitary multi-lumen (lobe)balloon can have various configurations including, for example,substantially oval or substantially triangular. Illustrative such shapesare shown in FIGS. 6a, 6b, 6c and 6d.

The present invention also comprises a method for opening a constrictedregion in the cardiovascular system of a patient especially in thosecases in which the lesion is non-concentric or eccentric. A ballooncatheter is provided in which the balloon portion is capable of beinginflated in such a manner that a higher dilation force (pressure) isexerted against a thicker (fat) portion of the constriction as opposedto the thinner portion of the constriction or non-diseased vessel. Afterthe selective application of greater pressure to the fat portion of theobstruction, the balloon is contracted and withdrawn from the body ofthe patient.

When the balloon catheter of the first embodiment of the presentinvention is employed the balloon catheter is inserted into thecardiovascular system of the patient with the balloon in an unexpandedcondition. After the balloon is within the obstructed region, theposition of the catheter is adjusted such that the larger balloon isadjacent to the thin portion of the eccentric obstruction and thesmaller balloon (or balloons) is adjacent the fat portion of theobstruction. The balloons are then inflated so as to perform dilation ofthe lesion, deflated and then withdrawn from the patient. Radiopaquemarkers can be provided on the balloon in order to guide the user in theproper placement of the balloon within the lesion.

When the balloon catheter of the second embodiment of the presentinvention is employed, the usual insertion is performed into thepatient. However, since this embodiment provides for selectiveinflation, positioning may not be required. If desired, radiopaquemarkers can be present to allow for visualization during the procedure.After insertion and placement of the balloon at the lesion site, thelumen(s) (lobe(s)) of the balloon are selectively inflated in such amanner that a greater force (pressure) is exerted by the balloon againstthe fat portion of the lesion as compared to the thin lesion portion ornon-diseased vessel wall. After dilation, the balloon lobes arecontracted and the balloon catheter is withdrawn from the patient.

It should be understood, however, that the foregoing description of thepresent invention is intended merely to be illustrative thereof and thatother embodiments and modifications may be apparent to those skilled inthe art without departing from its spirit.

What is claimed:
 1. A method for treating a constricted region in ablood vessel, said constricted region having first and second portionsdisposed in a plane orthogonal to the blood vessel, comprising the stepsof:inserting into the blood vessel a dilatation catheter having adilatation element affixed thereto; locating the dilatation element insaid constricted region; establishing contact between said dilatationelement and said first and second portions of said constricted region;and applying a first, diffuse, cushioned dilatation force to said firstcontacted portion of said constricted region disposed in said plane anda second, focused, dilatation force to said second contacted portion ofsaid constricted region disposed in said plane, said second dilatationforce being higher than said first dilatation force.
 2. A method fortreating a constricted region in a blood vessel, the constricted regionincluding first and second portions disposed in a plane orthogonal tothe blood vessel, comprising the steps of:inserting into the bloodvessel a dilatation catheter having first and second dilatation balloonmembers disposed thereon, the dilatation balloon members being disposedeccentric to each other; locating the dilatation balloon members in saidplane; inflating said balloon members so as to establish contact betweensaid first and second dilatation balloon members and said first andsecond portions of said constricted region disposed in said plane,respectively, and so as to apply a first, diffuse, cushioned dilatationforce to said first contacted portion of said constricted regiondisposed in said plane and a second, focused, dilatation force to saidsecond contacted portion of said constricted region disposed in saidplane, said second dilatation force being higher than said firstdilatation force.
 3. The method recited in claim 2 which furthercomprises the step of inflating each of said balloon members at adifferent pressure.
 4. The method recited in claim 2 wherein said firstballoon member is inflated with a lower pressure than that of the secondballoon member.
 5. A method for treating a constricted region in a bloodvessel, the constricted region including a plane orthogonal to the bloodvessel, the constricted region including first and second portions, thesecond portion having a greater degree of constriction than the firstportion comprising the steps of:inserting into the blood vessel adilatation catheter having first and second dilatation balloon membersdisposed thereon, the dilatation balloon members being disposedeccentric to each other; locating the dilatation balloon members in saidplane, with said first dilatation balloon being disposed adjacent saidfirst portion of the constricted region and the second dilatationballoon being disposed adjacent said second portion of the constrictedregion; and inflating said balloon members so as to establish contactbetween said first and second dilatation balloon members and respectivefirst and second portions of said constricted region disposed in saidplane and so as to apply a first, diffuse, cushioned dilatation force tosaid first contacted portion of said constricted region disposed in saidplane and a second, focused, dilatation force to said second contactedportion of said constricted region disposed in said plane, said seconddilatation force being higher than said first dilatation force.